It is well known in orthopedics to immobilize a knee in extension for protection after injury or surgery, and numerous commercial devices are available for this purpose. One family of such devices use a series of multiple stays with close fitting panels and straps to keep the leg in the normal neutral position, offered by the Tecnol Company. Other similar devices offer an immobilizer molded as a plastic shell that conforms generally to the posterior of the limb, with four extension arms retaining straps for attachment of the device to the leg (such as offered by Watco Products Inc., depicted in U.S. Pat. No. 4,111,194, issued Sep. 5, 1978.). Other types of more expensive or complicated hinged braces also are available.
However, to applicant's knowledge, all such prior known devices are designed to keep the knee in a neutral or even a slightly flexed position. Further, all such devices are designed for close contact with the knee and the leg, leaving little room for accommodation of any supplemental cold and compression type dressings which have proven in recent years to advance healing.
In recent years it has become known that recovery after some types of surgery, such as anterior cruciate ligament reconstruction (ACL) is enhanced if the knee is kept in extension or maximal extension equal to that attainable in the opposite healthy leg. Such full extension it is believed precludes the formation of scar tissue within the joint during the initial healing period and helps insure a full range of motion after recovery.
Loss of motion (LOM) has recently been recognized as the most common complication following ACL reconstruction. A 24% incidence of a knee flexion contracture greater than 5 degrees following ACL reconstruction has been reported. This finding correlated positively with quadriceps weakness and patellofemoral pain. LOM is defined as a knee flexion contracture greater than or equal to 10 degrees or knee flexion less than 125 degrees or both. All patients with LOM experienced loss of extension and two thirds also had an associated loss of flexion. Patients who developed LOM used a postoperative brace that limited full extension more often than patients who had normal motion following surgery. This loss of full extension following ACL reconstruction may have adverse functional implications that may lead to an abnormal gait, quadriceps weakness, or patellofemoral pain. This recently has been reported in the "The Anterior Cruciate Ligament;" by Freddie H. Fu, M.D., Clinics in Sports Medicine, Vol. 12, No. 4, October 1993.
Postoperative management following ACL reconstruction to reduce the risk of LOM emphasizes inter alia early restoration of full extension symmetric to the noninvolved knee, early range of motion and quadriceps exercises, and restoration of normal gait. Cold and compression, (such as that provided by the Cryocuff.TM. (produced by applicant's assignee Aircast Inc., Summit, N.J.)), also are used to reduce postoperative inflammation.
The appropriate amount of knee extension is highly individual and may vary during the early period of post operative recovery. None of the known non-hinged immobilizers is capable of providing this highly desirable, individualized maximal extension of the leg in a convenient and cost effective manner.